Drying of tomato pomace in daylight simulated photovoltaic‐assisted drying system: Effects of daylight intensity and application mode

Abstract

AbstractIt was aimed to dry a by‐product of tomato paste production (tomato pomace) by minimizing the losses valuable components and reducing energy consumption. In this concept, a daylight simulated photovoltaic‐assisted dryer (DPVD) applying the daylight in different modes and intensities during drying was custom‐designed. The effects of daylight applications on the change of some quality characteristics of tomato pomace and system performance characteristics were investigated, and the optimum drying condition was determined. The process conditions included the combination of three different daylight application modes (UV‐blocked daylight via solar tube‐DLST, DLST + LED, and LED) and three different daylight intensities (2,500, 7,500, and 10,000 lux). The drying was applied for 240 min at constant air temperature (60°C) with an air velocity of 2 m/s. The moisture content and the water activity values of dried tomato pomace were 8.86 ± 2.00% and 0.57 ± 0.10%, respectively. The lycopene and β‐carotene losses after drying were determined as 68.36 ± 4.32% and 65.66 ± 4.33%, respectively. The energy and exergy efficiencies of the system were in the range of 19.56%–35.73% and 5.10%–17.05%, respectively. The optimum condition meeting the criteria of superior quality and high‐performance characteristics was obtained by applying DLST at 7,500 lux (desirability 0.728). In the performance improvement studies, it has been concluded that all the energy required for the process could have been fulfilled as 100% from solar energy with the support of photovoltaic panels. In other words, it was demonstrated that the developed DPVD system could be used to dry the tomato pomace not only in terms of providing high food quality and safety, but also in terms of having high energy efficiency.Practical applicationsExposure to the daylight is important to dry some foods. Especially in north countries, products are dried in artificial dryers, but it requires high energy consumption. In this study, the daylight transfer system was integrated into the artificial dryer for the purpose of using daylight effect in addition to the photovoltaic (PV) assistance for using solar energy. During periods when the solar thermal effect is not intense or in countries where the sun effect is limited, it will be possible to dry food products with the daylight effects via using the DPVD system in suitable microbiological conditions.In this study, tomato pomace samples, which are the byproduct of tomato paste production, could be dried in daylight simulated PV‐assisted drying system in high quality and with low energy consumption. It is concluded that it can be possible to obtain valuable components from a byproduct having no economical value.